why does my tailwheel retract only work when only my tailwheel retract is plugged in to the retracts y harness?

all retracts work individually. wing wheels work fine alone or together and whether tailwheel is connected or not.

all i can think is that the wing retracts(with replaced motor units), are sucking up the power and drawing it away from the tail. but I'm using a 4s 4000mah fully charged so that shouldn't be a problem should it? maybe the circuitry in the servoless unit is doing something mystical...

any ideas?

also might be relevant, its a hobbyking A-1 1800mm. it is renowned for its weak retracts. as stated i replaced the servoless unit- there is now some resistance on the wheel as it goes up and down and i am experiencing related problems. BUT, these I can work through; its the above issue that has me stumped. ---not even a click buzz or whir from the tail when the others are plugged in.--- EVEN if the tail is retracting and i plug in one of the wings it will stop dead and cease to work while the others go fine(by fine i mean they do as well as i have managed. its a work in progress).